Recently, there has been increasing demand for higher sensitivity and more improved image quality.
One of the key factors affecting the sensitivity of a silver halide light-sensitive material and the quality of an image is silver halide grains. Efforts have been made in the art to develop silver halide grains for higher sensitivity and image quality.
It is generally known that image quality can be improved by employing silver halide grains with smaller grain sizes. However, such smaller grain sizes inevitably lower the sensitivity of a light-sensitive material and therefore, it is difficult to balance the sensitivity with the image quality.
There have been studied the methods of improving both sensitivity and image quality by controlling a sensitivity/size ratio of the silver halide grains. The examples thereof are the use of tabular silver halide grains, which are disclosed in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 111935/1983, 111936/1983, 111937/1983, 113927/1983 and 99433/1984. These tabular grains have a larger surface area than those of regular octahedral, tetradecahedral and dodecahedral silver halide grains each having the same volume. Such larger surface area permits the silver halide grains to adsorb a larger amount of a sensitizing dye on the surface thereof and therefore to have an improved sensitivity.
Japanese Patent O.P.I. Publication No. 92942/1988 discloses tabular silver halide grains having therein a core of high AgI; Japanese Patent O.P.I. Publication No. 163451 discloses tabular hexagonal grains; and Japanese Patent O.P.I. Publication No. 163451/1988 discloses tabular silver halide grains having an aspect ratio of not less than 5. These methods can improve sensitivity and graininess to some extent, however, are insufficient for balancing a sensitivity with an image quality.